The word "more unfertile" suggests a condition or place that is even less able to promote life or growth than it already is. Some potential antonyms for this phrase could include "more fertile," "more productive," "more fruitful," "more bountiful," "more fecund," or "more prolific." All of these words suggest a greater abundance of life, growth, or resources than the original phrase. They imply the ability to support more diverse and vibrant ecosystems, greater agricultural yields, or more prolific reproduction. By using antonyms like these to describe a place or condition, we can evoke a sense of hope and possibility, suggesting that with the right care and attention, it is possible to transform even the most barren landscapes into thriving havens for life.